The amygdala is critically involved in human psychiatric diseases such as alcohol addiction, depression, bipolar illness, and anxiety disorders. A better understanding of the functional microcircuitry within the primate amygdala is required for insight into the pathophysiology of these human disorders. The principle goal of this project is to optimize methods that will allow differential visualization and electrophysiological recording from specific populations of interneurons based on differential cell-type specific promoter usage. The tools that will be created and optimized here will be applicable to a large range of neuroscience questions across most species. The specific experiments proposed in this project are aimed toward understanding the rat and primate amygdala. The amygdala offers a particularly rich substrate for research because it is among the best understood brain regions in terms of complex mammalian behavior. However, what remains to be determined is how the complex heterogeneity of neurons within the amygdala encodes and modulates information flow, and how activity in this neural circuit relates to behavior. The primary limitation to progress in this area is a lack of tools for examining neuronal functioning in defined neural populations. A second limitation is that there are sufficient dissimilarities in receptor expression and functional modulation between the rodent amygdala and that of higher primates to make translational research problematic. We intend to consolidate molecular biology, electrophysiology, and optical techniques into a united research approach to overcome these limitations. This R21 developmental grant hypothesizes that fluorescence-based reporters can be transiently expressed by cell-type specific promoters in neurons within organotypic slice cultures of the rodent and primate amygdala. Interneurons of basolateral amygdala can be divided into distinct subgroups based on the expression pattern of four marker genes: Parvalbumin, Cholecystokinin, Somatostatin, and Vasoactive Intestinal Peptide. These interneuron subgroups are thought to play distinct roles in modulating the input/output properties of excitatory pyramidal neurons within the amygdala. The defined promoters for these genes will be cloned upstream of a red fluorescent reporter (DsRed). Following the demonstration of efficient cell-type specific expression, visually-guided whole-cell patch clamp recordings of fluorescent interneurons wjll be obtained, and electrophysiological properties determined. Post-hoc dual immunofluorescent labeling will be used to verify the phenotype of each recorded neuron. Finally, defined promoters will be expressed in a lentivirus to determine how recordings from subacute slice cultures compares to recordings from acute brain slices following in vivo infection and expression of cell-type specific reporters. These experiments will advance our understanding of the primate amygdala, a necessary step for understanding the pathophysiology of and development of novel treatments for disorders of alcohol addiction and other psychiatric disorders.